This invention relates to paper containing electroconductive materials. In particular, it relates to paper rendered electroconductive by a layer or coating of electroconductive composition.
Electroconductive paper may be used to distribute electrical stresses in various insulating products; see U.S. Pat. No. 3,148,107. Where electrically conductive paper is to be used for nonimpact printing, a substrate, backing, impregnation coating or layer of electrically conductive material is usually constructed. See Vaurio and Fird, "Electrically Conductive Paper for Nonimpact Printing," Tappi, December, 1964, volume 47, No. 12, pages 163A-165A.
Various types of nonimpact printing processes are known as electrostatographic, electrophotographic, electrographic, "Electrofax" and other processes. As a rule, such processes call for the placement of an electric charge on the paper, which may be accomplished by a corona discharge, for example. The charge is, in most processes, placed on the paper in darkness. The paper may also contain a photo-responsive or photo-conductive layer or material, now popularly a specially treated zinc oxide which causes the charge to be dissipated in an area where light strikes it, thus leaving a pattern of the charged areas which is a reproduction of the image desired. The charged area attracts a powdered or other usually particulated image-forming material which may be fused or otherwise treated to make the image permanent. Other processes differ in that the image is created by electrical dissipation of the static charge in nonimage areas. In this and other processes (see Vaurio and Fird, supra), the common characteristic is an electrically conductive base paper.
Probably the most common system at present is the direct electrostatic process; see "Chemical & Engineering News," July 20, 1946, pages 88-89; U.S. Pat. No. 3,052,539. This process is similar to the xerographic method copy reproduction, except that the conductive substrate is built into paper rather than being on a separate drum or other device.
A well known electrically conductive material for use in nonimpact printing is described in U.S. Pat. No. Re-28,543. Among the electroconductive materials described therein is diallyl ammonium chloride.